The usual or default setting is E-TTL...which is auto flash metering. The exposure should be pretty accurate, unless your subject is fooling the meter by reflecting a lot or very little light.
You can adjust the flash exposure away from the 'meter reading' by adjusting the FEC...which can be done on the flash or on the camera body with most models.
The benefit of a flash like this, is that you can bounce the light...try that and see what you think.